Metrics Assessment and Streamflow Modeling under Changing Climate in a Data-Scarce Heterogeneous Region: A Case Study of the Kabul River Basin

Abstract

Due to many uncertainties in hydrological data and modeling, the findings are frequently regarded as unreliable, especially in heterogeneous catchments such as the Kabul River Basin (KRB). Besides, statistical methods to assess the performance of the models have also been called into doubt in several studies. We evaluated the performance of the Soil and Water Assessment Tool (SWAT) model by statistical indicators including the Kling-Gupta efficiency (KGE), Nash–Sutcliffe efficiency (NSE), and the coefficient of determination (R2) at single and multi-outlets in the KRB and assessed the streamflow under changing climate scenarios i.e., Representative Concentration Pathways (RCP) 4.5 and 8.5 (2020–2045). Because of the heterogeneous nature of the KRB, NSE and R2 performed poorly at multi-outlets. However, the KGE, as the basic objective function, fared much better at single-outlet. We conclude that KGE is the most crucial metric for streamflow evaluation in heterogeneous basins. Similarly, the mean and maximum annual streamflow is projected to decrease by 15.2–15.6% and 17.2–41.8% under the RCP 4.5 and 8.5, respectively.

Assessment of Water Resources under Climate Change in Western Hindukush Region: A Case Study of the Upper Kabul River Basin

“…Sohaib et al [42] found future seasonal shifts in the streamflow and the rainfall shifts at the Nowshera and Chitral watershed of KRB, and Ref. [18] found that the peak hydrograph split into two peaks; one formed in Mar-Apr indicated earlier snowmelt, and the second one in August, which was due to Monsoon rains increased in the Alingar watershed of the KRB. Our study suggests that the total runoff in the UKRB is expected to increase under RCP4.5 and RCP8.5, except for the 2090s in the RCP8.5 scenario.…”

“…Also, Ref. [18] conducted a study to assess the performance of SWAT, evaluate different statistical metrics during calibration and validation, and analyze the impacts of climate change on streamflow from 2020 to 2045 in the Alingar Watershed of the KRB. The results from Ref.…”

“…The results from Ref. [18] showed that the mean annual streamflow will see a decline of 15.2% to 15.6% by 2045 under RCP 4.5 and 8.5 scenarios in the Alingar watershed. However, uncertainty in their results was larger due to lacking bias corrections of RCMs and using only one RCM (RegCM4).…”